Freshwater algal diversity of the South-Tajik Depression in a high-mountainous extreme environment, Tajikistan

Abstract

The research on algal communities' response to altitude and altitude-related climatic conditions is sparse. So far, a full, accessible list of algae from the water bodies of the South-Tajik Depression has not been available. We compiled an algal species list of 1190 taxa that were revealed by us or listed in references in the South-Tajik Depression high-mountain rivers Kafirnigan, Vakhsh, Kyzylsu, Yakhsu, and Tairsu and in the lakes of its basin. The altitude gradient of the studied area is about 2500 m above sea level. An altitude-related algal diversity analysis was done with help of statistics and bioindication. The Willis curve for the distribution of species to genera had a trend line of R 2 = 0.92. A multivariate analysis was used for quantitative estimates of the ecological tolerance ranges of critical species and for detecting cardinal factors and trends at local water bodies to global levels of biodiversity evolution. Our analysis shows that species distribution was strongly affected by altitude and altitude-related climatic variables. Statistical methods revealed that temperatures stimulate algal species diversity, while precipitation and altitude suppress it. One of the floristic complexity criteria is the average species richness of the algal genera or the infraspecies to species ratio, which increased from 1.12 to 1.20 and reflects increases in structural complexity with altitude. Therefore, high altitude stresses algal communities and stimulates species polymorphism as a compensatory mechanism for algal species survival. Our approach is pertinent to the problem of floristic differentiation under climate change and climatic instability.

Algal Indication of Climatic Gradients

“…4). Can be seen that the role of diatoms in aquatic habitats of the Pamir Mountains is significantly decreased with increasing of habitat altitude [15]. Similar distribution we revealed for the Caucasus Mountain algal diversity (Fig.…”

“…Material for this study comes from the last twenty years of research in the rivers and lakes of Eurasia [6][7][8][9][10][11][12][13][14][15][16][17].…”

“…Remarkable that outstanding point such as 1.19 (Georgian Natural Reserves), 1.21 (Diatoms of Europe), 1.21 (Viliuy Reservoir, Yakutia) are summarized large sets of long-term scale information [30]. The Tajik Depression flora has even 1.43 Index [15], but it is not only large scale regional and time series, but also high mountain biome.…”

Comparative Analysis of Diatom Algae Diversity in the Pamir Protected Lakes, Tajikistan

“…Earlier we revealed altitude as one of the influencing factor on the level of habitats up to 2,600 m a.s.l. and also high latitude [24,25]. More of them, the index value that we calculated for the Pamir mineral springs algal communities was 1.24.…”

Algal Flora and Ecology of the High Mountain Lakes in the Artabel Lakes Nature Park (Gümüşhane, Turkey), I- Bacillariophyta

“…Earlier, S. Barinova [24] found that the Willis curve can be used as criteria for fullness of species list because the distribution follows the hyperbolic shape in well-studied algal floras in Eurasia. Therefore, we can do floristic, taxonomic and ecological analysis for the diatom flora in the Artabel Lakes Nature Park and compare it to other high mountain lake floras in this region where the Willis proportion also closely follows the hyperbolic shape [24][25][26][27][28]. One of the important characteristics of the Artabel Lakes Nature Park diatom flora is the composition of the dominant algae genera.…”